In FIG. 1, a cross-section of the self-stiffened, preimpregnated composite panel comprised of a base skin 1, on one face of which are added U-shaped stiffeners 2 placed parallel and side-by-side and each of them separated by an interfacing structure including a nail 3 and a nail-head 4 between them, the nail being formed of two half-nails 3a and 3b placed symmetrically, and the nail-head 4 filling in the space remaining between the skin 1, on the one hand, and the edges adjoining the half-nails 3a and 3b, on the other hand, is represented.
The skin 1, and also the U-shaped stiffeners 2 and the half-nails 3a and 3b, are comprised of superimposed plies formed of fabric or layers of carbon fibers preimpregnated with an appropriate resin. The stiffeners 2, the half-nails 3a and 3b, and the nail-heads 4 generally run the entire length of the panel.
An object of the invention is to simplify and perfect the type of panel shown in FIG. 1.
More specifically, the self-stiffened panels that are the subject of this invention are of a type comprised of a skin generally formed by several superimposed plies of preimpregnated carbon fibers, with the addition of U-shaped stiffeners added side-by-side, parts joining the branches of the U that are flattened against said skin with interposition, between the adjoining branches of two adjacent stiffeners, of an interfacing structure commonly called a “nail,” completed by a “nail-head” comprised of a cord of filling resin.
Still more specifically, the present invention aims to simplify and perfect the type of panel with U-shaped stiffeners illustrated in FIG. 1 from the attached drawings whose interfacing structure includes a nail formed of two half-nails placed symmetrically and a nail-head placed between the edges adjoining the half-nails, and involves a particular step of forming the half-nails.